Liquid crystal display device with repair structure

ABSTRACT

A liquid crystal display device with a repair structure that facilitates repair of a short circuit or an open circuit. In the device, a gate line is formed on an insulating substrate and a gate electrode is integral to the gate line. A semiconductor layer is formed on the gate electrode with having an insulating film therebetween. A data line is crossed with the gate electrode, and a source electrode is integral to the data line on the semiconductor layer and the gate electrode. A drain electrode is spaced oppositely the source electrode. A protective film has a first contact hole at the drain electrode. A pixel electrode is formed on the protective film and is connected, via the contact hole, to the drain electrode. The pixel electrode has an area overlapped partially with the data line and is spaced from the gate line by a desired length (α) at one or more corners thereof. A storage electrode extends from the pixel electrode to be overlapped partially with the gate line and is spaced from the data line by a desired width (δ) at one or more corners thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a liquid crystal display device, and moreparticularly to a liquid crystal display device that facilitates therepair of defects caused by open or short circuits.

2. Description of the Related Art

Generally, a liquid crystal display (LCD) has a gradually widening rangeof applications owing to its characteristics such as light weight, aslim profile, low power consumption, etc. Accordingly, the LCD has beenused for office automation equipment and video/audio equipment, etc.

Referring to FIG. 1, the conventional LCD includes a source electrode 16branched from a data line 8 to apply a data signal, and a gate electrode20 branched from a gate line 14 to apply a scanning signal. The LCD alsoincludes a drain electrode 18 for applying an image signal to a pixelelectrode 10. A number of data lines 8 are provided in a verticaldirection at a lower glass 2 (shown in FIGS. 2 and 3) to transmit thedata signal applied from a data driver (not shown) to each sourceelectrode 16. A number of gate lines 14 are provided in a horizontaldirection at the lower glass 2 to be crossed with each data line 8 totransmit a scanning signal applied from a gate driver (not shown) toeach gate electrode 20. A scanning signal transmitted from the gate line14 is applied to the gate electrode 20 to turn on a thin filmtransistor, thereby transmitting a data signal applied to the sourceelectrode 16 to the drain electrode 18. In other words, the gateelectrode 20 switches the data signal in correspondence with thescanning signal. A data signal transmitted to the drain electrode inthis manner is applied to the pixel electrode 10, and an orientation ofthe liquid crystal is changed to correspond with a level of a datasignal applied between the pixel electrode 10 and the common voltagelayer (not shown).

In this case, since the pixel electrode 10 is a region through which alight beam is transmitted, the larger the pixel electrode area, thehigher the aperture ratio of the pixel. Accordingly, as shown in FIG. 1,the pixel electrode 10 is overlapped with the gate line 14 and the dataline 8 so as to implement a liquid crystal display device with a highaperture ratio. To this end, an organic protective film with arelatively low dielectric constant of about 2.7 such as Benzocyclobutene(BCB) is used. In this case, since a dielectric constant of the organicprotective film is low, it becomes possible to overlap the pixelelectrode with the data line. A liquid crystal display device with ahigh aperture ratio can be implemented by overlapping the pixelelectrode with the data electrode in this manner.

A structure of the data line 8 taken along II-II′ line in FIG. 1 will bedescribed in conjunction with FIG. 2. As shown in FIG. 2, a gateinsulator (GI) 4 is formed on the upper portion of the lower glass 2. Atthe upper portion of the GI 4, a semiconductor layer 6 and the data line8 are sequentially provided. A protective film 12 is coated on the dataline 8 and the GI4. The pixel electrode 10 is provided at the upperportion of the protective film 12 so as to overlap with the data line 8at a desired distance.

Further, a structure of the gate line 14 taken along III-III′ line inFIG. 1 will be described in conjunction with FIG. 3. As shown in FIG. 3,the gate electrode 14 is formed selectively at the upper portion of thelower glass 2. The GI 4 is entirely coated on the gate electrode 14. Theprotective film 12 is coated on the GI 4. The pixel electrode 10 isprovided at the upper portion of the protective film 12 so as to overlapthe gate line 14. In order to implement a liquid crystal display devicewith a high aperture ratio, the gate line 14 and the pixel electrode 10,or the data line 8 and the pixel electrode 10, are overlapped at adesired distance with respect to each other.

In the above-described liquid crystal display device with a highaperture ratio, a distance between the pixel electrodes 10 is narrowenough to generate a short between the adjacent pixel electrodes (e.g.,(n,n) and (n+1, n)). Upon generation of the short, a point defect occursat the corresponding pixels. To cure such a short, a cutting laser isconventionally used. For example, if the (n,n) numbered pixel electrodeand the (n+1,n) numbered pixel electrode at the data line 8 is cut alonga cutting line 9 (shown in FIG. 1) so as to cut any one of these pixelelectrodes when they are shorted together, then the pixel electrodeoverlapping the gate line 14 must also be cut. In this case, a shortcircuit is generated between the gate line 14 and the pixel electrode 10by such cutting. On the other hand, a similar process is performed whenthe (n,n) numbered pixel electrode and the (n+1,n) numbered pixelelectrode at the gate line 14 are shorted, so that a short circuit isgenerated between the data line 8 and the pixel electrode 10 by suchcutting. The conventional liquid crystal display device with a highaperture ratio has a problem in that a successful repair is impossibleupon such a short between adjacent pixel electrodes.

FIG. 4 is a plan view of the conventional liquid crystal display devicewhen the data line and the gate line thereof are open. As shown in FIG.4, an open circuit is generated at the gate line 14 or the data line 8.For example, as shown in FIG. 5, in order to repair an open circuit inthe data line 8, the first point P1 and the second point P2 are weldedwith a separate pattern (or a repairing line) to reform an electric pathof the open-circuited data line 8. Similarly, during an open circuit ofthe gate line 14, an electric path of the open-circuited gate line 14 isreformed in the same manner. As described above, the conventional liquidcrystal display device requires a separate pattern or line to repair theopen-circuited line. As a result, a new scheme for appropriatelyrepairing an open circuit and a short circuit generated in the liquidcrystal display device with a high aperture ratio is required.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aliquid crystal display device with a repair structure that is capable ofappropriately repairing defects caused by the short circuit or the opencircuit.

In order to achieve these and other objects of the invention, a liquidcrystal display device suitable for repair according to an aspect of thepresent invention includes a gate line connected to an integrally formedgate electrode; a data line crossing the gate line, and connected to anintegrally formed source electrode; a protective film formed on the gateline and on the data line; a pixel electrode formed on the protectivefilm and connected to a drain electrode, a first portion of the pixelelectrode overlapping the data line and being laterally spaced a firstdistance from the gate line; and a storage electrode connected to thepixel electrode and overlapping the gate line.

A liquid crystal display device suitable for repair according to anaspect of the present invention includes a gate line connected to anintegrally formed gate electrode; a data line crossing the gate line,and connected to an integrally formed source electrode; a protectivefilm formed on the gate line and on the data line; a pixel electrodeformed on the protective film and connected to a drain electrode, aportion of the pixel electrode overlapping the data line; and a storageelectrode connected to the pixel electrode and overlapping the gateline, a portion of the storage electrode being laterally spaced adistance from the data line.

A method for repairing a short circuit between two adjacent pixels of aliquid crystal display device, each pixel having a pixel electrode whichdoes not overlap with a conductive line in corners of the pixelelectrode, according to another aspect of the present invention includescutting with a laser along a cutting line between two corners of thepixel electrode in either of the two adjacent pixels.

A method for repairing a break in a conductive line of a liquid crystaldisplay device according to another aspect of the present inventionincludes welding an overlapping portion of a pixel electrode on one sideof the break to the conductive line with a laser; welding theoverlapping portion of the pixel electrode on an opposite side of thebreak to the conductive line with the laser; and cutting the overlappingportion of the pixel electrode with a laser adjacent to the conductiveline.

A repaired liquid crystal display device according to another aspect ofthe present invention includes a conductive line formed on a substrate;a protective film formed on the conductive line; a pixel electrodeformed on the protective film; and a portion of the pixel electrodeoverlapping the conductive line and electrically separated from thepixel electrode by a gap.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will be apparent from thefollowing detailed description of the embodiments of the presentinvention with reference to the accompanying drawings, in which likeelements in different figures will be labeled with like referencenumbers, and in which:

FIG. 1 is a plan view showing the structure of a conventional liquidcrystal display device with a high aperture ratio;

FIG. 2 is a sectional view of the liquid crystal display device takenalong II-II′ line in FIG. 1;

FIG. 3 is a sectional view of the liquid crystal display device takenalong III-III′ line in FIG. 1;

FIG. 4 is a plan view of the conventional liquid crystal display devicewhen the data line and the gate line thereof are shorted;

FIG. 5 is a view for explaining a conventional method of repairing anopening in a line;

FIG. 6 is a plan view showing the structure of a liquid crystal displaydevice with a repair structure according to a first embodiment of thepresent invention;

FIG. 7 is a sectional view of the liquid crystal display device takenalong VII-VII′ line in FIG. 6;

FIG. 8 is a sectional view of the liquid crystal display device takenalong VIII-VIII′ line in FIG. 6;

FIG. 9 is a plan view showing the structure of a liquid crystal displaydevice with a repair structure according to a second embodiment of thepresent invention;

FIG. 10 is a sectional view of the liquid crystal display device takenalong X-X′ line in FIG. 9;

FIG. 11 is a plan view showing the structure of a liquid crystal displaydevice with a repair structure according to a third embodiment of thepresent invention;

FIG. 12 is a view for explaining a repairing method for the liquidcrystal display device according to the third embodiment of the presentinvention;

FIG. 13 is a plan view showing the structure of a liquid crystal displaydevice with a repair structure according to a fourth embodiment of thepresent invention; and

FIG. 14 is a view for explaining a repairing method for the liquidcrystal display device according to the fourth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 6. there is shown a liquid crystal display device witha repair structure according to a first embodiment of the presentinvention that includes a pixel electrode formed in such a manner to bespaced with a gate line 34 and a data line 28. As shown in FIG. 7 (takenalong line VII-VII′ in FIG. 6), in the liquid crystal display device ofFIG. 6. the gate line 34 is formed on an insulating substrate 22 and agate electrode 34′ is integral to the gate line 34. A gate insulator(GI) 24 is provided at the upper portion of the gate line 34. At theupper portion of the GI 24, the data line 28 and a semiconductor layer26 are formed in such a manner to be crossed with the gate line. Asource electrode 36 is formed integral to the data line 28, and a drainelectrode 38 is spaced oppositely to the source electrode 36.Subsequently, a protective film 32 having a desired thickness isprovided. A first contact hole 37 is defined at a position correspondingto a drain electrode part 38 in the protective film 32. The firstcontact hole 37 connects the pixel electrode 30 and the drain electrodepart 38 electrically.

Meanwhile, an organic protective film is used as the protective film 32,and different types of organic film are as indicated in the followingtable:

TABLE 1 Type and Dielectric constant of the organic protective film Typeof Organic Protective Film Dielectric Constant Polymide added withFluoropolyarylether 2.7 Teflon 1.9-2.1 Cytop 2.1 BCB (BenzoCycloButene)2.7 Fluoropolyarylether 2.6 Para-Xylene added with Fluoropolyarylether2.4

As shown in FIG. 6, storage electrode 42′, formed of a materialidentical to the pixel electrode 30, extends from the pixel electrode 30and overlaps a portion of the gate line 34. The corner of the storageelectrode 42′ is spaced from the data line 28 by a desired width δ forthe purpose of permitting a repair. An aperture ratio of a pixel may beimproved by providing a gate line overlapping part 33 at a bottomportion of the pixel electrode 30 which overlaps the gate line 34 asneeded. The gate line overlapping part 33 and the storage electrode 42are spaced by a desired width δ from the data line. The desired width δmeans a length permitting a repair of the pixel electrode 30. It isdesirable that the length α and the width δ spaced from the pixelelectrode 30 are set to correspond with a resolution of the laserperforming repair work, so that a short circuit is not generated by thecutting of the laser. For instance, a resolution of the laser used for arepair work is usually about 5 μm.

FIG. 7 is a sectional view showing side corners of the gate line 34along line VII-VII′ in FIG. 6. As shown in FIG. 7, the GI 24 and theprotective film 32 are formed at the upper portion of the lower glass22. In this case, an organic protective film as indicated in Table 1 isused as the protective film 32. The pixel electrode 30 is provided atthe upper portion of the protective film 32. The pixel electrode 30 andthe gate line 34 are spaced by a desired length α. The desired length αmeans a distance permitting a repair of the pixel electrode 30 by alaser without generation of a short circuit.

FIG. 8 is a sectional view showing side corners of the data line 28along line VIII-VIII′ in FIG. 6. As shown in FIG. 8, the GI 24 and theprotective film 32 are formed at the upper portion of the lower glass22. In this case, an organic protective film as indicated in Table 1 isused as the protective film 32. The pixel electrode 30 is provided atthe upper portion of the protective film 32. The pixel electrodes 30 andthe data line 28 are spaced by a desired width δ. The desired width δmeans a distance permitting a repair of the pixel electrode 30 by alaser without generation of a short circuit.

A method of repairing the (n,n) numbered pixel electrode and the (n+1,n)pixel electrode in FIG. 6 when they are shorted will be described. Tothis end, any one of the two pixel electrodes is cut with the laser. Forinstance, the (n,n) numbered pixel electrode is cut along a cutting line40 with the laser. Thus, the short-circuited (n,n) and (n+1,n) numberedpixel electrodes are electrically isolated from each other. Accordingly,point defects of the short-circuited pixel electrodes 30 can be removedwithout generation of a short circuit. Also, a repair can be performedby a similar method when the (n,n) numbered pixel electrode and the(n,n+1) numbered pixel electrode are shorted together.

Referring now to FIG. 9, a liquid crystal display device with a repairstructure according to a second embodiment of the present inventionincludes a pixel electrode 30 spaced from a gate line 34. The structureof this second embodiment is similar to that of FIG. 6, so only thedifferences will be described. The upper and lower portions of the pixelelectrode 30 are spaced by a desired length a from the gate line 34 forthe purpose of permitting a repair. A storage electrode 42 is formed ofa material identical to the pixel electrode 30 and overlaps with thegate line 34. The storage electrode 42 and the pixel electrode 30 areelectrically connected via a second contact hole 39. The storageelectrode 42 is spaced from the data line 28 by a desired width δ fromthe data line. At this time, it is desirable that the length α and thewidth δ spacing the respective gate and data lines from the pixelelectrode 30 are set to correspond with a resolution of the laser foravoiding short circuits caused by laser cutting. For instance, aresolution of the laser used for repair work is usually about 5 μm.

FIG. 10 is a sectional view of the liquid crystal display device takenalong X-X′ line in FIG. 9. As shown in FIG. 10, the gate electrode 34 isformed at the upper portion of the lower glass 22. The storage electrode42 overlapped with the gate electrode 34 is electrically connected tothe (n,n+1) numbered pixel electrode by the second contact hole 39. Inthis case, the (n,n) numbered pixel electrode is spaced by a desireddistance α from the gate line 34.

An aperture ratio decreases by about 1% in comparison to the liquidcrystal display device shown in FIG. 6 by spacing the upper and lowerportions of the pixel electrode 30 from the gate line 34 by a desiredlength α. However, the number of point defects in the pixel electrodeconnected vertically becomes almost “0” because a distance between the(n,n) numbered pixel electrode and the (n,n+1) numbered pixel electrodeis sufficiently wide.

Meanwhile, when the (n,n) numbered pixel electrode and the (n+1,n) pixelelectrode in FIG. 9 are shorted together, any one of the two pixelelectrodes is cut with a laser so as to repair them. For instance, the(n,n) numbered pixel electrode is cut along a cutting line 40 with thelaser. Thus cut, the short-circuited (n,n) and (n+1,n) numbered pixelelectrodes are electrically isolated from each other. Accordingly, pointdefects of the short-circuited pixel electrodes 30 can be removed.

Referring to FIG. 11, a liquid crystal display device with a repairstructure according to a third embodiment of the present inventionincludes a pixel electrode 30 spaced from a gate line 34. The structureof this third embodiment is similar to that of FIG. 9, so only thedifferences will be described. The upper and lower portions of the pixelelectrode 30 are spaced by a desired length α from the gate line 34 forthe purpose of permitting a repair. The pixel electrode 30 is overlappedwith a data line 28. In this case, a storage electrode 42 is formed insuch a manner to be overlapped with a portion of the gate line 34. Thestorage electrode 42 and the pixel electrode 30 are electricallyconnected via a contact hole, similar to the structure of FIG. 9.

A method of repairing the data line 28 in FIG. 11 when it isopen-circuited will be described in conjunction with FIG. 12. As shownin FIG. 12, one side point P3 at which one side of open-circuited dataline 28 is overlapped with the pixel electrode 30 is welded by a laser,thereby electrically the data line 28 and the pixel electrode 30. Theother side point P4 at which other side of open-circuited data line 28is overlapped with the pixel electrode 30 is welded by a laser, therebyelectrically the data line 28 and the pixel electrode 30. Subsequently,the connected points P3 and P4 in the open-circuited data line areelectrically isolated from the rest of the pixel electrode 30 by cuttingthe pixel electrode 30 along a cutting line 40, so that the data line isrepaired.

Referring to FIG. 13, a liquid crystal display device with a repairstructure according to a fourth embodiment of the present inventionincludes a pixel electrode 30 spaced from a gate line 34 and a data line28. The structure of this third embodiment is similar to that of FIG. 6,so only the differences will be described. The four corners of the pixelelectrode 30 are spaced by a desired length α from the gate line 34while being space by a desired width δ from the data line 28 for thesake of permitting a repair. The gate electrode 34, the data line 28 andthe pixel electrode 30 are overlapped with each other except for thefour corners of the pixel electrode 30.

A method of repairing the data line 28 and the gate lines in FIG. 13when they are open-circuited will be described in conjunction with FIG.14. As shown in FIG. 14, one side point P3 at which one side ofopen-circuited data line 28 is overlapped with the pixel electrode 30 iswelded by a laser, thereby electrically one side of the data line 28 andthe pixel electrode 30. The other side point P4 at which the other sideof open-circuited data line 28 is overlapped with the pixel electrode 30is welded by a laser, thereby electrically the other side of the dataline 28 and the pixel electrode 30. Subsequently, connected points P3and P4 in the open-circuited data line are electrically isolated fromthe rest of the pixel electrode 30 by cutting the pixel electrode alonga cutting line 40, so that the data line is repaired. In the similarmanner, the gate line 34 can be repaired by connecting two points P5 andP6 at the open-circuited gate line 34 electrically by welding andcutting the overlapping portion of the pixel electrode 30.

As described above, the liquid crystal display device with a repairstructure according to the present invention has an advantage in that aprocess yield can be improved by arranging the pixel electrode incorrespondence with a short circuit or open circuit of the electrode forthe sake of permitting a repair thereof.

Although the present invention has been explained by the embodimentsshown in the drawings described above, it should be understood to theordinary skilled person in the art that the invention is not limited tothe embodiments, but rather that various changes or modificationsthereof are possible without departing from the spirit of the invention.Accordingly, the scope of the invention shall be determined only by theappended claims and their equivalents.

1. A liquid crystal display device suitable for repair, comprising: agate line connected to an integrally formed gate electrode; a data linecrossing the gate line, and connected to an integrally formed sourceelectrode; a protective film formed on the gate line and on the dataline; a pixel electrode formed on the protective film and connected to adrain electrode, wherein a first portion of the pixel electrode overlapsthe data lines, and the pixel electrode is laterally spaced a firstdistance from the gate electrode; and a storage electrode extended fromthe pixel electrode and overlapping the gate line.
 2. The liquid crystaldisplay device of claim 1, wherein a portion of the storage electrode islaterally spaced a second distance from the data line.
 3. The liquidcrystal display device of claim 2, wherein the first and seconddistances are about 5 μm respectively from the gate line and the dataline.
 4. The liquid crystal display device of claim 2, wherein the firstportion of the pixel electrode and the portion of the storage electrodeare located in at least one corner of the pixel electrode.
 5. The liquidcrystal display device of claim 1, wherein a second portion of the pixelelectrode overlaps a data line adjacent to the data line overlapped bythe first portion of the pixel electrode.
 6. The liquid crystal displaydevice of claim 1, wherein the first portion of the pixel electrodeextends along an entire side of the pixel electrode.
 7. The liquidcrystal display device of claim 5, wherein the second portion of thepixel electrode extends along an entire side of the pixel electrode. 8.The liquid crystal display device according to claim 1, wherein thestorage electrode is integral to the pixel electrode and is formed of amaterial identical to the pixel electrode.
 9. The liquid crystal displaydevice according to claim 1, wherein the storage electrode is formedfrom an identical material to the pixel electrode and is connected tothe pixel electrode via a contact hole defined in the protective film.10. The liquid crystal display device according to claim 1, wherein thepixel electrode includes: a gate overlapping part overlapping a gateline on a side of the pixel electrode opposite from the storageelectrode.
 11. The liquid crystal display device according to claim 1,wherein the pixel electrode includes four sides and four corners, thefour corners being laterally spaced from the data and gate lines, andtwo of the four sides laterally overlapping adjacent data lines.
 12. Theliquid crystal display device according to claim 11, wherein at leastone of the four sides laterally overlaps a gate line.
 13. The liquidcrystal display device according to claim 1, wherein the protective filmis an organic insulating film having a dielectric constant of 1.5 to3.0.
 14. The liquid crystal display device according to claim 13,wherein the protective film is made from Benzocyclobutene (BCB).
 15. Aliquid crystal display device suitable for repair, comprising: a gateline connected to an integrally formed gate electrode; a data linecrossing the gate line, and connected to an integrally formed sourceelectrode; a protective film formed on the gate line and on the dataline; a pixel electrode formed on the protective film and connected to adrain electrode, a portion of the pixel electrode overlapping the dataline, and the pixel electrode being spaced a predetermined distance fromthe gate electrode; and a storage electrode overlapping the gate lineand extended from and connected to the pixel electrode, a portion of thestorage electrode being laterally spaced a distance from the data line.